Special Issue Highlights Environmental Toxins and Autism

Date: 
April 25, 2012

 

This week’s issue of the journal Environmental Health Perspectives features a set of articles on autism risk and environmental toxins. The articles discuss the biological mechanisms by which exposure to these toxins may affect brain development and provides a “Top Ten” list of culprits that should be given high priority by researchers.

The special issue grew out of a symposium, “Exploring the Environmental Causes of Autism and Learning Disabilities,” co-sponsored by Autism Speaks at the Mt. Sinai Children’s Environmental Health Center in December 2010. The workshop’s goal was to create an action plan for the discovery of environmental risk factors of autism spectrum disorder (ASD) and other neurodevelopmental disorders in children. (The papers, in their entirety, can be found here, here, here and here.)

“This landmark meeting was an important first step for further development of research programs looking at gene and environment interactions in autism,” says Alycia Halladay, Ph.D., director of research for environmental sciences at Autism Speaks. “We are pleased that some of the ideas could be published in a peer-reviewed journal for others to read and consider.”

It is well recognized that autism results from the disruption of normal brain development during prenatal development and/or very early life. Genetic studies have pointed to genes that regulate how brain cells connect to each other. There is now growing evidence that certain environmental factors, including chemicals, can similarly affect brain development, in doing so, may increase the risk for autism and other developmental disorders.

It is important to note that while environmental exposures are implicated in the development of autism, this appears to be in combination with underlying genetic predisposition to this developmental disorder, Halladay notes.

As reported in this week’s special issue, the 2010 symposium also generated a list of ten chemicals considered highly likely to contribute to autism and other NDDs. These chemicals, already widely distributed in the environment, show evidence of developmental neurotoxicity.

They are:

1. Lead

2. Methylmercury

3. PCBs

4. Organophosphate pesticides

5. Organochlorine pesticides

6. Phthalates

7. Bisphenol A

8. Automotive exhaust

9. Polycyclic aromatic hydrocarbons

10. Brominated flame retardants

“Of great concern is that a large number of the chemicals in widest use have not undergone even minimal assessment of potential toxicity, and only about 20 percent have been screened for potential toxicity to early development,” write Philip Landrigan, M.D., Luca Lambertini, Ph.D. and Linda Birnbaum, Ph.D., in an accompanying editorial. This list, they write, is intended to focus autism research in directions most likely to produce important findings in the near future. The list is not meant to be exhaustive, Landrigan notes, nor should this call for research replace government safety testing on these and other potentially toxic chemicals in our environment.

Reform of safety testing of potentially toxic chemicals in the environment is an issue that affects the entire globe and is of a high priority in the autism community. Autism Speaks recently joined the Safer Chemicals Healthy Families Coalition, which is urging reform of the Toxic Substances Control Act. Learn more about the coalition and its activities here. In addition, Autism Speaks recently reported on recommendations for minimizing exposure to some of these potential toxins, as published in the American Journal of Obstetrics and Gynecology.

You can learn more about Autism Speaks-supported research on environmental exposures here.